Al4

Page 1

№ 1092 1) =

a + 2  2a 2 − a − 3 2a − 3  a + 2  2(a + 1)(a − 3 2 ) a − 2   = = ⋅ : a − 2  a 2 + 5a + 6 a − 2  a − 2  (a + 2 )(a + 3) 2a − 3 

a + 2 2(a + 1)(a − 3 2 ) a−2 a +1 ⋅ ⋅ = a − 2 (a + 2 )(a + 3) 2(a − 3 2 ) a + 3

1  8b 2 + 8b + 2 2b + 1 2b + 1 b(b − 4) 2b + 1 (b − 4 )  2)  2 +  : ⋅ = ⋅ ⋅ = b b b b 2b b 2 − 4b  2(2b + 1)2

№ 1093 1)

= − + +

a a2 − 1

+

a2 + a − 1 a3 − a 2 + a − 1

+

a2 − a − 1 a3 + a 2 + a + 1

2a 3

=

a4 − 1

a a2 + a − 1 a2 − a − 1 + 2 + 2 − (a − 1)(a + 1) a (a − 1) + (a − 1) a (a + 1) + (a + 1) 2a 3

(a − 1)(a + 1)(a 2 + 1) 2

a − a −1

(a + 1)(a

2

)

+1

a2 − a −1

(a + 1)(a

(

2a

3

(a − 1)(a + 1)(a 2 + 1)

=

2a 3

)

=

(a − 1)(a + 1)(a 2 + 1) a (a 2 + 1) + (a 2 + a − 1)(a + 1) + (a 2 − a − 1)(a − 1) − 2a 3 = (a − 1)(a + 1)(a 2 + 1) 2

)

a a2 + a − 1 + + (a − 1)(a + 1) (a − 1) a 2 + 1

=

+1

Преобразуем числитель полученной дроби а(а2+1)+(а2+а–1)(а+1)+(а2–а–1)(а–1)–2а3=а3+а+а3+а2+а2+а–а–1+а3 – – а2 – а2 + а – а + 1 – 2а3 = а3 + а, тогда дробь примет вид

a3 + a

(a − 1)(a + 1)(a 2)

=

2

1 2

a + 5a + 6

1

)

) (a −1)(a + 1)

+1

+

(

a a 2 +1

=

2

2a 2

a + 4a + 3

+

2a

2

+

=

a 2

a −1

1

(a + 1) +

2

+ a +1

1

2 = a+3

2

(a + 2)(a + 3) (a + 1)(a + 3) (a + 1)(a + 2 ) a + 3 1 ⋅ (a + 1) + 2a (a + 2 ) + 1 ⋅ (a + 3) − 2(a + 1)(a + 2 ) = = (a + 1)(a + 2 )(a + 3) = 146

=

a + 1 + 2 a 2 + 4 a + a + 3 − 2a 2 − 6 a − 4 0 = =0 (a + 1)(a + 2)(a + 3) (a + 1)(a + 2)(a + 3)


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